1. Field of the Invention
The present invention relates generally to an apparatus for stacking can blanks and transferring the stacked blanks to the feed hopper of a can welder.
2. Description of the Related Art
In the making of three-piece cans, in other words those cans having a generally cylindrical body and separate end caps, the can body is formed of blanks cut from sheet metal, the blanks being formed into a cylinder and welded in a welder. First, sheets of metal are fed into a slitter which generally cuts the sheet metal in two perpendicular directions to form a plurality of can blanks. The blanks must be transferred into the feed hopper of the welder/former. Heretofore, workers were hired to gather and stack the blanks, block the stacks to assure their alignment, and carefully place the blanks into the feed hopper as needed. Permitting the feed hopper of the welder to run out of blanks unnecessarily interrupts the can making operation. However, an excessive number of blanks in the feed hopper may result in jamming of the blank feeder. In addition, the blank feeder for the welder may also jam when stacks of blanks are allowed to drop into the feed hopper from more than a predetermined height.
An apparatus for transporting can blanks and the like is disclosed in U.S. Pat. No. 5,122,030 for feeding can blank stacks to a welder hopper as needed. The apparatus disclosed therein includes a chain conveyor for catching the blanks as they are fed from the slitter output and moving the blanks laterally to the end of the conveyor, where the blanks are thrown into a stack forming location on a turntable having a number of stack holding locations. The stack forming location includes a reciprocating member to abut and thereby align the blanks into a stack. The turntable is rotatable to move other stack locations into position at the end of the conveyor, thereby moving the just-formed stack into a holding position on the turntable. Once the turntable moves a stack into a position in alignment with a transport gantry, a gripper on the end of a vertical arm is lowered to grip the stack, lift the stack, and transport the stack horizontally into a position over the welder hopper. The stack is then lowered and released by the gripper onto the top of the previously transported can blanks in the welder hopper.